Prevent or warn users if they are creating a tekton bundle that will be too large for etcd

Feature request

Since the contents of a tekton bundle will have to fit within an etcd value, tkn bundle push should validate that the extracted bundle will not be too large. While testing of the bundles should reveal that content is too large, it is possible for k8s deployments to customize that size. Therefore, it is possible that testing of tasks will not catch content that is too large.

Since the size limit imposed by etcd is configurable, the default for this should be able to be overridden if needed.

Use case

As a Tekton developer, I want to generate tekton bundles that will successfuly resolve as tasks in a k8s cluster.

UI Example

N/A

The issue names tkn bundle push as the entry point; begin there and trace bundle extraction and any existing size or configuration handling. Done means the command detects an extracted bundle beyond the configured limit, warns or prevents creation, and permits the default limit to be overridden; add coverage for the limit and override.